In order to control a device at a predetermined frequency, an inverter circuit will be used to rectify commercial ac power to dc power, and then convert the dc power to ac power that is controlled at a predetermined frequency.
The inverter circuit is formed by combining a rectifying stack, a smoothing condenser, a power transistor, and the like. These circuit components continue to be integrated, and an intelligent module which packages a drive circuit and a power element together is now being marketed. In addition, one type of electric power unit needed to drive the inverter includes a converter that rectifies commercial ac power to dc power, and improves harmonic suppression and efficiency. Moreover, it has been proposed that this electric power unit employs a power switch and the like.
The converter that converts commercial ac power to dc power, and the inverter that converts dc power to ac power of a predetermined frequency, are comprised of heat generating components such as diodes and power switches, and thus must include a heat dissipating structure. For example, it is possible to achieve a cooling effect on the electrical components by using an aluminum substrate to mount the electrical components, due to the cooling effect provided by the surface of the aluminum substrate that is opposite the mounting surface.
However, because the integration of these electrical components continue, a great deal of heat will be generated thereby and the heat dissipating capabilities of the aluminum substrate will be insufficient. Because of this, it is thought that the heat dissipating capabilities will improve by fixing a large number of plate shaped heat dissipating fins onto the bottom surface of the aluminum substrate.
When the heat dissipating plates are added, efficient heat transfer cannot be expected at the connecting surface between the aluminum substrate and the heat dissipating fins because the portion that connects these two elements has a great deal of heat resistance. In order to address this problem, increasing the size of the heat dissipating fins to increase the heat dissipating capacity thereof has been considered. However, this will increase the overall size of the device and make it difficult to lower costs.
It is an object of the present invention to provide a power module that has an efficient heat dissipation structure, that is small, and that allows cost to be lowered.
In addition, because there are many instances in which the converter and inverter are placed in barracks or in specialized modules, the shape of the completed component is large, the thermal design thereof must take into consideration its spatial layout design and thermal state, and the design of the converter and inverter will be extremely difficult.
In addition, a controller for controlling the inverter circuit is comprised of a microcomputer, and the controller and the inverter circuit are connected by a harness or the like. When a drive signal is transmitted via this harness, there is a concern that noise will be easily transferred and be involved in malfunctions.
Furthermore, there are other problems that it is difficult to diagnose a failure part, it is difficult to specify the components to exchange and it is complicate to exchange a component, since the control of the inverter is high efficient.
Because there is a great deal of exposed solder, component lead, and the like for mounting each component, there is also a concern that tracking accidents will occur due to the infiltration of corrosion, dust, or small animals therein.
Operational control of an air conditioner is conducted by controlling the amount of refrigerant that circulates in the refrigerant circuit with the compressor. This type of compressor uses an inverter circuit to control the operational frequency thereof, and thus includes the problems with the inverter circuit described above. In particular, it is desirable for the air conditioner to be made compact by reducing the size of each component therein, and to simplify the layout and thermal design thereof. Furthermore, there is a need to prevent malfunctions due to the effects of noise, as well as a need to prevent the ill effects of corrosion, dust, and the infiltration of small animals therein. In particular, when the inverter circuit is installed in the outdoor unit of an air conditioner, there are concerns about the deterioration thereof that accompanies environmental changes such as temperature variations over a long period of time and wind and rain, and the infiltration of insects and other small animals. The effects of these problems need to be eliminated to the greatest degree possible.
It is another object of the present invention to provide a power module that is constructed such that the portions thereof that are exposed, such as the harness, the solder, and component leads, are reduced to the greatest degree possible, the effects of noise are eliminated, the effects of corrosion, dust, and the infiltration of small animals are eliminated, and special layout and thermal designs are not necessary.